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Journal : Indonesian Journal on Geoscience

Metamorphic Rock-Hosted Orogenic Gold Deposit Type as a Source of Langkowala Placer Gold, Bombana, Southeast Sulawesi Idrus, Arifudin; Nur, I.; Warmada, I. W.; Fadlin, Fadlin
Indonesian Journal on Geoscience Vol 6, No 1 (2011)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.6.1.43-49

Abstract

DOI: 10.17014/ijog.v6i1.114In 2008, placer gold was discovered in Langkowala area (Bombana Regency), Southeast Sulawesi, Indonesia, and more than 60,000 traditional gold miners in the early 2009 have been operating by digging vertical pits and panning active stream sediments. The grade of placer gold ranges from 50 to 140 g/t. Local geological framework indicates that the placer gold is not related to volcanic rock-related hydrothermal gold deposit, e.g. epithermal, skarn or porphyry. This paper describes a preliminary study on possible primary deposit type as a source of the Langkowala (Bombana) secondary placer gold. A field study indicates that the Langkowala (Bombana) placer/paleoplacer gold is possibly related to gold-bearing quartz veins/veinlets hosted by metamorphic rocks particularly mica schist and metasediments in the area. These quartz veins/veinlets are currently recognized in metamorphic rocks at Wumbubangka Mountains, a northern flank of Rumbia Mountain Range. Sheared, segmented quartz veins/veinlets are of 2 cm to 2 m in width and contain gold in a grade varying between 2 and 61 g/t. At least, there are two generations of the quartz veins. The first generation of quartz vein is parallel to foliation of mica schist and metasediments with general orientation of N 300oE/60o; the second quartz vein generation crosscut the first quartz vein and the foliation of the wallrock. The first quartz veins are mostly sheared/deformed, brecciated, and occasionally sigmoidal, whereas the second quartz veins are relatively massive. The similar quartz veins/veinlets types are also probably present in Mendoke Mountain Range, in the northern side of Langkowala area. This primary gold deposit is called as ‘orogenic gold type’. The orogenic gold deposit could be a new target of gold exploration in Indonesia in the future.
Thermal and Infrared Studies of Garnierite from the Soroako Nickeliferous Laterite Deposit, Sulawesi, Indonesia Sufriadin, Sufriadin; Idrus, Arifudin; Pramumijoyo, S.; Warmada, I. W.; Nur, I.; Imai, A.; Imran, A. M.; Kaharuddin, Kaharuddin
Indonesian Journal on Geoscience Vol 7, No 2 (2012)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17014/ijog.7.2.77-85

Abstract

DOI: 10.17014/ijog.v7i2.137Mineralogical characterization of some garnierite samples from Soroako have been conducted using X-ray diffraction, thermal analysis, and infrared spectroscopy methods. XRD patterns reveal the samples mainly containing the mixture of kerolite (talc-like phase) and serpentine with minor smectite, sepiolite, and silica. Thermal analyses of garnierite samples indicated by DTA curves are in good agreement with patterns that have been reported in literature. Three endothermic peaks normally occur in the ranges between 58º C and <800º C illustrating three steps of weight losses: adsorbed, bound, and hydroxyl/crystal water. One additional weight loss in low temperature region of sepiolite is corresponding to the lost of zeolitic water. Infrared spectra appeared in 3800 - 3200 cm-1 region generally exhibit broad absorption bands, indicating low crystallinities of studied samples and can be assigned to the presence of hydroxyl group bonded to octahedral coordination mainly Mg atom. The bands observed at 1660 cm-1, 1639 cm-1, 1637 cm-1, and 1633 cm-1 in all samples indicate water molecules. FTIR spectra displaying the strong bands at 1045 cm-1, 1038 cm-1, and 1036 cm-1 could be related to the presence of Si-O-Si bonds linking to tetrahedral coordination. The strong absorption bands appeared at 511 cm-1, 505 cm-1, 499 cm-1, and 496 cm-1 in respective samples are attributed to divalent cation bonds (e.g. Mg, Ni-O). Both TG/DTA and FTIR seem to be the powerful tool in diagnosing the crystal chemistry of garnierite which is mainly composed of phyllosilicate minerals.
Co-Authors A. Harijoko A. Imai A. Imai A. M. Imran A. W. Yogatama Agung Harijoko Agus Prasetya Ahmad Aminuddin, Muhammad Irman Khalif bin Akira Imai Al-Furqan, Reza Aldian Fahrialam Alvian Rizky Yanuardian Anastasia Dewi Titisari Anita Yuliyanti Anita Yuliyanti Ariffin, Kamar Shah Arifudin Idrus Arifudin Idrus Arifudin Idrus Arifudin Idrus Atmaja, Ammar Dwi Aulia Rahmah Karunianti Aung Tay Zar Aung Tay Zar, Aung Tay Bhakti H. Harahap Bhakti H. Harahap Bunchoeun Pich Chusni Ansori Denizar Rahman Dian Novia Sartika Dian Yesy Fatimah Diyan Aditya Putra Pratama Doni Prakasa Eka Putra Ega Gita Prasastia Endah Retnaningrum Endah Retnaningrum Endang Tri Wahyuni F. Pratiwi Fadlin Fadlin Fadlin Fadlin Fadlin Fadlin Fadlin, Fadlin Franz Michael Meyer Franz Michael Meyer Franz Michael Meyer, Franz Michael Gevor, Even Hakim, Fahmi Haryono, Septiawan Nur Hasria Hasria Hasria Hasria Hasria Hasria, Hasria Herry Yogaswara Heru Hendrayana Hideki, Ohta Himawan Tri Bayu Murti Petrus Hirajima, Tsuyoshi Htun, Tin May I Gde Budi Indrawan I. G. Sukadana I. Nur I. Nur I. Nur Imai, A. Imai, Akira Irzal Nur Irzal Nur, Irzal Iwan Setiawan Jochen Kolb Johan Syafri Mahathir Ahmad Kaharuddin Kaharuddin Kaharuddin, Kaharuddin Kamar Shah Ariffin Kant, Win Kha Yay Oo Khant, Win Koichiro Watanabe Koichiro Watanabe Koichiro Watanabe Koichiro Watanabe Koichiro Watanabe Koichiro Watanabe, Koichiro Kolb, Jochen Kotaro Yonezu Kusumaningrum, Serafica Btari Christiyani Kyaw Linn Zaw Leonardo Anthony Wijaya Linn Zaw, Kyaw Listiyastuti, Riana Lucas Donny Setijadji Makruf Nurudin Martadiastuti, Vanadia Maulana, Deviana Shinta Mochammad Aziz Mochammad Aziz, Mochammad Mudinillah, Adam Muhammad Irman Khalif bin Ahmad Aminuddin Muhammad Zulfikrie Mutiara Selvina Myo Min Tun Myo Min Tun Myo Min Tun Naing Oo, Toe Nugroho Imam Setiawan Nur, I. Nur, I. Nurwijayanti Okki Verdiansyah Okki Verdiansyah Okki Verdiansyah Oo, Than Than Pich, Bunchoeun Pramumijoyo, Pranayoga Pramumijoyo, S. Pranayoga Pramumijoyo Prasastia, Ega Gita Putra Pratama, Diyan Aditya Rahman, Denizar Retno Hartati Reza Al-Furqan Riyadi, Hasan Rodhie Saputra S. Pramumijoyo S. Pramumijoyo Salafudin Salafudin, Salafudin Sang Kompiang Wirawan Saputra, Rodhie Sartika, Dian Novia Seang Sirisokha Septiawan Nur Haryono Shinta Maulana, Deviana Simamora, Lestari Sutra Sirisokha, Seang Soewondo, Widiasmoro Subagyo Pramumijoyo Subagyo Pramumijoyo, Subagyo Sufriadin, Sufriadin Sukmandaru Prihatmoko Sukmandaru Prihatmoko Syafruddin Maula Syafruddin Maula T. B. Adimedha Takemura, Jiro Tetsuro Yoneda Than Than Oo Tin May Htun Toe Naing Oo Tsuyoshi Hirajima Tsuyoshi Hirajima Tun, Myo Min Ubaidillah, Aji Syailendra Vanadia Martadiastuti Wahyu Wilopo Wawan Budianta Widiasmoro Soewondo Win Kant Win Khant Yoneda, Tetsuro Yonezu, Kotaro Yonezu, Kotaro